Recent advances in miniaturization have led to the development of microfluidic systems that are designed, in part, to perform a multitude of chemical and physical processes on a micro-scale. Typical applications include analytical and medical instrumentation, industrial process control equipment, liquid and gas phase chromatography, and the detection of biological weapons. In this context, there is a need for devices that have fast response times to provide precise control over small flows as well as small volumes of fluid (liquid or gas) in microscale channels. In order to provide these advantages, microarrays are typically integrated on microfluidic chips. The term “microfluidic chip” refers to a system or device having microchannels or microchambers that are generally fabricated on a substrate. The length scale of these microchannels is typically on the micron or submicron scale, i.e., having at least one cross-sectional dimension in the range from about 0.1 micron to about 500 microns.
The development of DNA gene microarray or “microarray” technology capable of detecting thousands of genes in a single experimental test has rapidly advanced and become a widespread application technology. Rapid discrimination of biomolecules such as gene sequences and proteins originating from viruses, bacteria, plants, algae, and eukaryotes such as mammalian cells is useful in a variety of fields, for example health care, food safety, drug testing and bioweapons defense. One drawback of microarray technology in its current format is the long and tedious processing times involved, often requiring up to four days for RNA/DNA sample preparation. Another drawback is that current systems are not designed for quick and portable sensing of biomolecules. In order to tackle these weaknesses in gene microarray analysis there is a need to develop compact systems that combines microfluidics, microarray discrimination, and microarray imaging to efficiently prepare, bind and detect sample target biomolecules.